Recently, as technology development and demand for mobile devices grow, demands for a rechargeable battery that can be charged/discharged have been rapidly increased as an energy source. Accordingly, various researches and studies with respect to a rechargeable battery that can fulfill various needs have been carried out. In addition, the rechargeable battery is also attracting attention as a power source of an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (Plug-In HEV), and the like, which have been suggested as a solution for solving air pollution caused by conventional gasoline vehicles and diesel vehicles using fossil fuels.
Thus, an electric vehicle (EV) that can be driven only by a rechargeable battery, a hybrid electric vehicle (HEV) that uses a battery and an existing engine together, and the like have been developed, and some of them have been commercially available. As a rechargeable battery of a power source of the EV, the HEV, and the like, a nickel hydrogen metal (Ni-MH) rechargeable battery has been mainly used, but, recently, a lithium rechargeable battery having high energy density, a high discharge voltage, and high output stability has been actively studied, and some are in the commercially available step.
When the rechargeable battery (or a battery cell) is used as a power source of a vehicle, the rechargeable battery is used in the form of a module having a structure in which a plurality of rechargeable batteries are connected because high power and high capacity are essential.
For example, a plurality of rechargeable batteries are electrically connected such that a single unit module is formed, and a plurality of unit cells may be manufactured as a high capacity and high output power source having an electrical connection structure by being connected in parallel, series, or a combination of parallel and series to modularize the unit modules. The structure in which the unit modules are assembled may be called a battery module in a broad sense.
Meanwhile, in order to use the battery module as a power source of, for example, a vehicle, which is a device or a system exposed to various environments, the battery module needs to maintain structural stability with respect to external impact according to various environments and needs to assure safety in various levels of humidity and temperature.
Thus, the battery module has a general structure where external members such as a case and a housing are assembled to protect the module structure and support the same, and the structure where the external members are assembled may be called a battery module assembly in a broad sense.
However, such a large-capacity battery module assembly has a significantly large volume so that a plurality of combining members, for example, extension bolts, brackets, combining bars, and the like are needed to combine the unit modules and the external members while maintaining capacity to be relatively high compared to the volume of the assembly. Accordingly, the structure becomes complicated and assembling may not be easy.
In particular, the combining members such as the extension bolts and the combining bars not only cause an increase of the number of parts for assembling, thereby increasing complexity in a manufacturing process of the battery module assembly, but also require additional space for engagement of the combining members, thereby causing an increase of the size of the space required for the battery module assembly.
Due to such factors, there is a problem with the battery module assembly in that it is difficult to have a simple structure in which constituent elements are simply combined while maintaining a small size, that is, a compact structure.
Accordingly, the need for a method for minimizing the entire volume of the assembly while having a structure in which the constituent elements are stably combined is high.